Freight discharge apparatus

ABSTRACT

A freight transportation system is provided and comprises a loading station, an unloading station and a vehicle moveable therebetween to transport freight. The vehicle includes a lower platform for carrying freight and a pair of doors moveable between open and closed positions. In the closed position, the doors constitute side walls to prevent removal of the freight from the vehicle. In the open position, the doors are located to facilitate removal of the freight from the vehicle. The unloading station includes a door moving mechanism for moving the doors of the vehicle to the open position upon its arrival at the station. A freight removal device moves the freight off of one side of the platform when the doors are moved to the open position.

This is a divisional application of application Ser. No. 07/516,965,filed Apr. 30, 1990, which is a continuation of Ser. No. 07/263,445,filed Oct. 27, 1988, now abandoned.

The present invention relates to freight transportation systems and moreparticular to arrangements for facilitating the unloading of freight.

Arrangements for transporting freight are well known in the art. Forlong distance freight transportation, large rail cars or trucks areutilized which are unloaded with specialized equipment such as fork lifttrucks. The time taken to unload the freight is small compared with thetransportation time and therefore is not of primary concern. There ishowever a need for transportation systems which convey freight over arelatively short distance and in which the time taken to unload is asignificant part of the overall handling time. An example of such anapplication is in airports when baggage must be transported betweenterminals. Conveyor belt systems have been typically used to avoidunloading but the speed at which the baggage is transported is slow andthe conveyor belt systems are prone to failure. Other baggage handlingarrangements have been considered which use gas powered carts fortransporting baggage. However, problems exist in these arrangements inthat the manpower required to remove the baggage from the carts once thebaggage has been transported, is expensive.

It is therefore an object of the present invention to obviate ormitigate the above disadvantages by providing a novel freight transportsystem.

According to one aspect of the present invention there is provided afreight transportation system comprising a loading station, an unloadingstation and a vehicle movable therebetween to transport freight, saidvehicle including a support platform to carry said freight and retainingmeans on the platform, said retaining means being movable from firstposition in which removal of freight is inhibited and a second positionin which removal of freight is permitted, said unloading stationincluding opening means operable on said retaining means to move itbetween said first and second positions upon arrival of the vehicle atsaid unloading station and freight discharge means operable to dischargefreight from the platform to one side of said vehicle.

In another aspect of the present invention there is provided a freighttransportation system comprising a loading station, an unloading stationand a vehicle moveable therebetween, said vehicle including a supportplatform to carry freight and a pair of doors located on opposite sidesof the said vehicle, said doors being moveable from a first position inwhich removal of freight is inhibited to a second position in whichremoval of freight is permitted, said unloading station includingopening means operable upon said doors when said vehicle is stationaryto move said doors concurrently to said second position to permitremoval of said freight.

In another aspect of the present invention there is provided a freighttransportation vehicle comprising a platform, a door located on oppositesides of said platform and each movable from a first position in whichthey inhibit removal of freight from said platform to a second positionin which they permit removal of freight from said platform, said doorsbeing pivotally mounted above their upper edge to cause movementlaterally away from said platform upon movement from said first positionto said second position.

In still yet another aspect of the present invention there is provided afreight discharge apparatus comprising a base, a boom mounted on saidbase and drive means operable to cause said boom to move across a planersurface and discharge freight therefrom.

An embodiment of the present invention will now be described by way ofexample only with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a freight transportation system;

FIG. 2 is a sectional view of the system illustrated in FIG. 1 takenalong line 2--2;

FIG. 3 is a side view of a portion of the system illustrated in FIG. 1;

FIG. 4 is a side view of an element of the portion illustrated in FIG.3.

FIG. 5 is a rear view of the system illustrated in FIG. 1 taken alongline 5--5;

FIG. 6 is a partial sectional view of the system illustrated in FIG. 5taken along line 6--6; and

FIG. 7 is a sectional view of a portion of the system illustrated inFIG. 6.

Referring to FIG. 1, a freight transportation system in the form of abaggage transport and removal system is generally shown at referencenumeral 10. The system 10 includes a track 12 having a pair of rails 14for supporting a wheeled baggage cart 16 powered by in track linearinduction motors (LIM's) (not shown). A door opening mechanism 18straddles the track 12 and opens the doors of the baggage cart 16 whenthe cart is in the unloading station. A baggage removing device 20 ispositioned on one side of the track 12 for removing the baggage from thecart 16. A roller set 22 is positioned on the other side of the track 12and receives the baggage after it has been pushed off of the cart 16. Aconveyor belt or carousel 24 receives the baggage from the roller set 22and transports the baggage at a reduced speed to its desired location.

Referring now to FIGS. 1, 2, 5 and 6 the cart 16 is better illustrated.As can be seen, the cart comprises a support platform 26 for supportingbaggage and two axle sets 28. The cart 16 includes a reaction rail 17secured to the undercarriage of the cart which extends along thelongitudinal axis of the cart. Linear Induction Motors primaries (notshown) are located between the rails of the track 12 at spaced intervalsfor energizing the reaction rail 17 to provide thrust for the cart 16.Guide wheels 29 project forwardly from the leading axle 28 to cooperatewith the track 12 and steer the axle sets along the track as shown inFIG. 5.

End walls 30 extend upwardly from either end of the platform and haveinclined upper edges 31.

Side frames 32 extend from each end wall 30 to provide support thereforand include sidewall elements 32a, beam elements 32b and a roof element32c aspanning the beam elements 32b. A pair of gull-winged doors 34 areprovided on the cart 16 with each door being located on opposite sidesof the cart. Since the doors 34 are identical only one will be describedherein. The door 34 includes two longitudinally spaced end wall portions34a which overly respective ones of the end walls 30. The diverging endof the end wall portions 34a are connected to opposite ends of a sidewall member 34b extending the length of the cart 16. The otherconverging end of the end wall portions 34a are pivotally connected tothe respective end wall 30 adjacent the upper portion thereof via a pinto define a hinge. Thus, when the doors 34 are in the closed position asshown in FIG. 1, the side wall members 34b define side walls for thecart and constitute retaining means for inhibiting removal of baggagestored thereon. The doors 34 may be swung upwardly about their hinges toan open position as shown in chain dot lines in FIGS. 2 and 5 to allowaccess to and egress from platform 26. Air springs 36 are connectedbetween the end walls 30 and the end wall portions 3a of the doors 34and provide vertical forces to counterbalance the weight of the doors 34so that they fall in a controlled manner under the influence of gravityto the closed position. The air springs 36 also limit the upwardpivoting movement of the doors 34 by the available extent of theirtravel.

The air springs 36 are located to allow a stable open position for thedoors 34 if they are operated manually. In this manner, the personunloading the cart does not have to hold the doors open when unloadingthe cart 16 once they have been lifted to this position. The air springs36 allow the doors 34 to move "overcentre" so that their centre ofgravity is inboard of the hinge point with the air springs 36 limitingfurther pivotal movement. To close the doors, the person merely has topush downwardly on the doors until the centre of gravity of the doors 34moves back outboard of the hinges when the air springs 36 will againcounterbalance the door

To control movement of the doors 34, a door release mechanism isprovided and generally indicated by reference 38. The mechanism 38 isconnected to each door 34 by a plate 44 as shown in FIG. 7. Since eachdoor release mechanism 38 is identical, only one will be describedherein. Each of the handles 38 is pivotally connected to a plate 44 bypins 46 and includes a handle 40 which extends forwardly from one end ofthe cart 16 to be engaged by the door opening mechanism 18 when thedoors 34 are to be opened. The handle 40 is connected to a latch 42 thatextends through the door 34. The latch 42 includes a vertical portion 48that terminates in a hook 50 at its lower end for engagement with alatch plate 52. The latch plate 52 is bolted to a bracket 54 secured tothe end wall 30 of the cart 16. The latch 42 is biased to the latchedposition relative to the latch plate 52 by a spring 56 acting betweenthe vertical portion 48 and the plate 44. Thus, with the latch 42 in thelatched position as shown in FIG. 7, vertical movement of the door 34 isprevented by engagement of the hook 50 with the plate 52. To release thelatches, the latch 42 is rotated about the pins 46 against the bias ofthe spring 56 so that the hook 50 clears the latch plate 52. Verticalmovement of door 34 may then occur. The release of the latch andmovement of the doors 34 is induced by the door operating mechanism 18as will now be described.

Referring now to the door opening mechanism 18 as best illustrated inFIGS. 1, 5, 6 and 7, the mechanism comprises a support frame 60 whichstraddles the track 12 with sufficient clearance to allow the cart 16 topass through. The frame 60 supports upper and lower pairs of gears 62and 64 respectively, the gears of each pair being located on oppositesides of the track 12 and rotatable about horizontal i The track a ax s.upper gears 62 are interconnected via a shaft 66 which extends at oneend through the support frame 60. A motor 68 is coupled to the one endof the shaft 66 and imparts rotation thereto via a gear box 69 therebyrotating the upper gears 62. Endless loops of chains 70,72 couple theupper and lower gears 62,64 on each side of the track 12 to cause thelower gears 64 to rotate with the upper gears 62 when the motor 68 isactuated. A horizontal crossbar 74 extends between the chains 70,72 andthus, moves with the chains when the motor 68 is actuated to describe avertical reciprocating motion along horizontally spaced runs.

The mechanism 18 is positioned at the unloading station so that thecrossbar 74 engages the handles 40 of a cart 16 at the unloading stationas it moves vertically upward under the influence of motor 68. Thiscauses the latches 42 to pivot about the pins 46 against the bias of thesprings 56 and move the hooks 50 out of engagement with the latch plates52. Continued upward movement of the crossbar 74 lifts the doors 34concurrently upward about the pivots to the position shown in chain dotline in FIG. 5, with the bar 74 at its upper limit whereupon the motor68 is interrupted. In this position, the platform 26 may be unloaded bythe baggage removing device 20.

Referring to FIGS. 2, 3 and 4, the baggage removing device 20 includes apushing plate 80 secured at either end to respective ones of a pair ofarm assemblies 82. The arm assemblies 82 are extendable and retractableto move the plate 80 across the platform 26 to push the baggage off ofthe cart 16. The other end of the arm assemblies 82 are pivotallyconnected to a plinth 84. The plinth 84 is resiliently secured to itssupport surface G by a bolt 85 and spring 86 to elevate the rear of theplinth 84. A drive assembly 88 is provided on the plinth 84 and iscoupled to the arms 82 for extending and retracting the arm assemblies82.

As shown, each arm assembly 82 comprises a pair of booms 90 and 92 and apair of attitude maintaining links 94 and 96 respectively. The lower endof the boom 92 and link 96 is pivotally connected at vertically spacedlocations to a bracket 98 mounted on the plate 80. A wheel 100 ismounted to the bottom of the bracket 98 and rests on the cart platform26 when the arm assemblies 82 are extended to push baggage from thecart. Inboard ends of the booms 90,92 are pivotally connected by pins105 to a housing 106. The housing 106 is provided with lugs 107 toreceive pins 109 and to connect pivotally the attitude maintaining links94,96 to the housing 106. Gear wheels 104,102 are mounted on the inboardends of booms 90,92 respectively within the housing 106 and mesh tocontrol relative pivotal movement between the booms 90,92.

The lower ends of boom 90 and link 94 are pivotally connected to theplinth 84 in spaced relation so that a parallelogram linkage is definedbetween the links 94, boom 90, plinth 84 and housing 106. Similarly, thelinks 96 and boom 92 define a parallelogram linkage between the housing106 and the bracket 98.

Movement of the arm assemblies is controlled by the drive assembly 88that comprises a bracket 108 on each boom 90. Each bracket 108 receivesa connecting rod 110 that is pivotally connected thereto via a pin 111.Each connecting rod 110 is connected at its other end to a crank 114keyed to drive shaft 112 extending in opposite directions from a gearbox 113. A motor 116 is coupled to the gear box 113 for rotating theshaft 112. Upon rotation of the drive shaft 112, the cranks 114 rotateand cause, through the connecting rods 110, pivotal movement of thebooms 90 about their connection with plinth 84. As the booms pivot, thelinks 94 maintain the attitude of housings 106 and therefore the pins105. The rotation of the booms 90 about pins 105 induce an oppositerotation of booms 92 about pins 105 through the interaction of gears102,104, causing an outward movement of the lower end of booms 92. Thelinks 96 act to maintain the vertical attitude of the plate 80 duringoutward movement of the booms 92 with additional vertical supportprovided by wheels 100. After 180° of rotation of the drive shaft 112,the arm assemblies 82 reach the limit of their travel and continuedrotation causes the arms to retract.

A controller 120 is provided to control operation of the baggage removaldevice 20 and the door opening mechanism 18. The controller 120 monitorsthe mechanism 18 and prevents the removal device 20 from operating untilthe doors of the cart 16 have been moved to the open position and thecart 16 is positioned accurately relative to the frame 60. Thecontroller 120 prevents the cart 16 from moving when the arms of theremoval device are in an extended position. Furthermore, the controller120 prevents the cart 16 from being moved within the frame when thecrossbar 74 is in a position below the upper surface of the cart.

A microswitch 118 is provided between the lower edge of the plinth 84and ground G to isolate the motor 116 if a "jam" occurs in the baggageto prevent advance of the pusher plate 80. This condition is sensed byan increased load on the plinth 84 from the arm assemblies 82 causingcompression of spring 86. This moves the elevated lower edge of theplinth 84 toward the ground G to open the microswitch 117 and interruptpower to the motor 116.

The unloading sequence will now be described assuming the arm assemblies82 are retracted as shown in FIG. 1 and the crossbar 74 is elevated asindicated in chain dot line in FIG. 5. The LIM driven cart 16 is movedthrough the frame 60 until it is properly located relative to thebaggage removal device 20 as determined by controller 120. When the cart16 is in the proper position, the motor 68 is actuated to move thecrossbar 74 from the elevated position to a position below the handles40. This movement occurs on the rearward vertical run of the chains70,72 so that the crossbar 74 is clear of the handles 40, as it movesdown. Continued rotation of the shaft 66 moves the crossbar 74 forwardlyand upwardly to engage the underside of the handles 40 to release thelatches and open the doors 34 as described above.

When the doors 34 are in the open position, the motor 68 is stopped sothat the crossbar 74 supports the handles 40. The controller 120 detectsthis condition and allows the motor 116 to be actuated to extend andretract the arm assemblies 82. This causes the plate 80 to sweep theplatform 26, thereby forcing the baggage off of the other side of thecart 16 and onto the roller set 22. From the roller set 22, the baggageis conveyed to the conveyor belt 24 where it can be transported at areduced speed.

When the baggage has been removed from the cart 16 and the armassemblies 82 of the removal device 20 have been fully retracted, thecontroller 120 inhibits further operation of the motor 116 and allowsthe motor 68 to be actuated until the crossbar 74 rotates over the uppergears 62. As this occurs, the crossbar 74 moves away from the cart andis removed from engagement with the underside of the handles 40 therebyallowing the doors 34 to fall closed into locking engagement. With thecrossbar 74 positioned above the cart, the controller 120 allows thecart 16 to be driven through the support frame 60 so that the next cartcan be unloaded in a similar manner.

It should be apparent that the cart need not be LIM driven but may bepowered by other sources. Furthermore, the doors of the cart need not be"gull-wing" shape so long as they do not impede with the movement of thearms of the removal device 20 when lifted to the open position. However,the "gull-wing" doors and the vertical lifting action to open the doorsensures that they cannot accidentally open when moving between loadingand unloading stations. The pusher mechanism also provides a robust unitwith the drive being in-line with the loads imposed and all disposed toone side of the cart 16.

We claim:
 1. A freight discharge apparatus comprising a base, a boommounted on said base and said boom including a pair of arms pivotallyinterconnected at one end with one of the arms pivotally connected atits opposite end to said base and pushing means mounted to the oppositeend of the other arms, and drive means operable to cause said pushingmeans to move substantially horizontally across a planar surface anddischarge freight therefrom, said drive means including a motor mountedon said base and having a drive shaft rotatable by the motor, a drivemember secured to said shaft and rotatable therewith and a driven memberhaving two ends, said driven member pivotally secured at one end to saidone arm and pivotally secured at the other end to said drive member at alocation spaced from the axis of rotation of said drive shaft to impartreciprocal pivotal movement of said arm relative to said base uponrotation of said drive shaft, and attitude maintaining means to maintainsaid pushing means in a predetermined disposition relative to saidsurface.
 2. Apparatus according to claim 1 wherein said pushing means isa pusher blade.
 3. Apparatus according to claim 1 wherein said attitudemaintaining means includes a pair of gear segments operable betweenadjacent ends of said arms and parallel link means extending from saidbase to said pushing means.
 4. Apparatus according to claim 1 includinga load sensor to monitor loads imparted on said boom and to inhibitoperation of said motor upon said loads exceeding a predetermined level.5. Apparatus according to claim 4 wherein said base is resilientlymounted on a support and said load sensor is responsive to relativemovement between said base and support.
 6. Apparatus according to claim1 wherein said drive shaft is located relative to the boom to applytensile force to said driven member upon movement of said boom from aretracted to a deployed position.
 7. Apparatus according to claim 6wherein said one arm pivots downwardly about a transverse horizontalaxis in said arm moving between said retracted and deployed position andsaid drive shaft is located below said boom and between said arms. 8.Apparatus as claimed in claim 1, wherein said planar surface is on awheeled vehicle and said base is mounted externally of said vehicle.